1. Field of the Invention
The present invention relates to a transmission apparatus, more particularly, relates to a design applying dual-ratchet wheels, gear set, and transmission wheel set with transmission chain or belt. Thereby, regardless of the drive wheel set rotating forward or backward, the driven shaft can rotate unidirectionally and output power.
2. Description of the Prior Art
Ratchet wheels are mainly used in transmitting intermittent motion, or used in mechanical apparatuses with unidirectionally rotating shaft, in which the shaft solely rotates in one direction and idly spins in another direction. Thus the ratchet wheels are widely implemented in kinds of mechanical transmission apparatuses.
Conventional ratchet wheel transmission apparatuses are widely used, such as the disclosures of Taiwan Patent No. 90201202, entitled in “transmission sports vehicle”. The prior art of reference discloses a transmission apparatus merged in a bike, and the transmission apparatus comprises a drive gear fixed on the pedal shaft for driving a driven gear, in which the driven gear is configured to transmit at least one unidirectional ratchet wheel set that rotates in reverse direction, and the driven gear then transmit a linking shaft that coaxially set with one small linking gear at each side thereof. The small linking gear at one side engages with the unidirectional ratchet wheel at one side of the driven gear, and the small linking gear at another side engages with a small gear, in which the small gear further engages with the unidirectional ratchet wheel at another side of the driven gear. Then, one linking gear of the linking shaft engages with a transmission gear, and the transmission element linking to the back wheel is centrally set on the shaft of the transmission gear for linking movement.
Another kind of ratchet wheel transmission apparatus is like the disclosures of Taiwan Patent No. 91107934, entitled in “driving forward apparatus of a bicycle”. It comprises a forward rotation driving portion and a backward rotation driving portion. The backward rotation driving portion comprises transferring portion for rotation direction, driving disk, and ratchet wheel. The forward rotation driving portion comprises a driving disk fixed on the pedal axle by an axle key, wherein the driving disk is externally set with a detent; therefore the forward rotation of the pedal axle is able to be transferred to a driving chain wheel by a ratchet wheel fixed on one side of the driving chain wheel. The transferring portion for rotation direction comprises a driving gear integrated with the driving disk and having a central portion supported by a bearing onto the pedal axle, in which the driving gear rotates in reverse direction referring to the pedal axle by rotation from a fixed gear on the pedal axle. The driving disk is externally set with the detent and is integrated with the driving gear of the transferring portion for rotation direction. The ratchet wheel is fixed on another side of the driving chain wheel and is linked to the detent. In any rotation direction of the pedal axle, the bicycle can be driven to go forward.
In the aforementioned configurations, the previous one discloses the transmission sports vehicle with the body having a frame and a handle, in which the frame is set with a front wheel and a back wheel below and is set with a modulated transmission apparatus set, and the transmission apparatus set is linked to a pedal set on the top of the frame, and is linked to the back wheel via a transmission element. Therefore, it achieves modulated transmission in small size, with efficient transmission, and artistic in shape.
The latter one comprises a forward rotation driving portion and a backward rotation driving portion. The forward rotation driving portion is fixed on the pedal axle for transferring the forward rotation force of the pedal arm to the chain wheel, and the back rotation driving portion is fixed on the pedal axle for rotating the chain wheel forward via a transferring portion for rotation direction that transfers the backward rotation force of the pedal arm into the forward rotation force. Therefore, even the pedal rotates backward; the bicycle can still be driven to go forward as the pedal rotates forward.
It is understood that in response to different transmission requirements, corresponding configurations of gear train and ratchet wheel set are required to meet a pre-determined performance. Thus, the inventor of the present invention develops a technology and configuration that can achieve unidirectional rotation output no matter the input rotates forward or backward.